Passive, portable blood storage system

ABSTRACT

A passive, portable system and a method for storing blood are disclosed. The system comprises a sealable thermal isolation chamber which is preconditioned at a certain temperature for a predefined period of time. The thermal isolation chamber includes cavities of a phase change material which help to maintain the temperature of bags of human blood that are placed into the thermal isolation chamber for storage during transit. The thermal isolation chamber is surrounded by vacuum insulation panels and the vacuum insulation panels, encompassing the thermal isolation chamber, is placed into a durable carrying bag. The thermal isolation chamber is reusable along with the vacuum insulation panels and bag.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application claims priority to provisional U.S. patent applicationSer. No. 60/535,844 filed on Jan. 12, 2004, which is incorporated hereinby reference in its entirety.

TECHNICAL FIELD

Certain embodiments of the present invention relate to the portablestorage of materials within a temperature range, such as for the storageof human blood in the field. More particularly, certain embodiments ofthe present invention relate to a portable system that maintains apredetermined temperature range for materials kept therein, such as bagsfilled with human blood, over a long period of time and withoutrequiring a source of power.

BACKGROUND OF THE INVENTION

A variety of materials are desirably maintained in a predeterminedtemperature for various purposes. For example, sensitive materials suchas human blood are often stored in non-portable, powered refrigerationunits to keep the blood at a temperature that will keep the blood fromgoing degrading and becoming unusable. When the blood needs to beremoved from a refrigeration unit and transported for use in the field(e.g., military combat situations, car accident victims, etc.) it isoften transported in an insulated container which may or may notcontain, for example, ice (i.e., frozen H₂O). However, such portablemethods of transportation often allow the temperature of the blood tofluctuate more than desired and do not typically keep the temperature ofthe blood within the desired range for a long enough period of time.Other materials are also desirably maintained at a predeterminedtemperature in environments which do not allow refrigeration or thelike.

As an alternative, a portable or semi-portable container with aninternal active power and temperature regulation system to regulate thetemperature within the container can be used. The active power systemmay include a battery or a fuel cell and a refrigerant system which addsto the complexity and weight of the container and may not have a desiredlevel of reliability (e.g., the battery may discharge at a faster ratethan desired). Another alternative is to use an external power source,such as a gasoline powered generator or external battery, which plugsinto a temperature regulation system of the container in order toregulate the temperature within the container. This requirestransporting the external power source along with the container.

It is desired to have a lightweight, highly reliable, portable containerwhich maintains the temperature of bags of human blood over a relativelylong period of time such that the blood can be administered to patientsmany hours after it was first placed into the container.

Further limitations and disadvantages of conventional, traditional, andproposed approaches will become apparent to one of skill in the art,through comparison of such systems with the present invention as setforth in the remainder of the present application with reference to thedrawings.

BRIEF SUMMARY OF THE INVENTION

An embodiment of the present invention comprises a portable system forstoring materials at a predetermined temperature range, such as humanblood. The system comprises a base unit, having a plurality of closedwalls and an open side, into which bags of human blood or othermaterials are placed. The closed walls of the base unit include internalcavities containing a phase change material. The system also includes alid having an internal cavity containing the phase change material. Thelid fits onto the open side of the base unit to seal the base unit whenstoring the bags of human blood. The system further comprises a vacuuminsulation material surrounding the base unit and lid and an outercarrying bag surrounding the vacuum insulation material.

Another embodiment of the present invention comprises a method forstoring materials, such as human blood. The method comprisespreconditioning a thermal isolation chamber at a preconditioningtemperature for a predefined period of time. The thermal isolationchamber comprises a base unit and a lid. The base unit has a pluralityof walls and an open side. The closed walls of the base unit and the lidinclude internal cavities containing a phase change material whichchanges phase at about a predetermined storage temperature. The methodalso includes placing at least one bag of human blood into the baseunit. The method further comprises placing a lid onto the open side ofthe base unit to seal the base unit. The method also includessurrounding the sealed base unit with a vacuum insulation material andplacing the sealed base unit, surrounded by the insulation material,into a carrying bag.

These and other advantages and novel features of the present invention,as well as details of an illustrated embodiment thereof, will be morefully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an exemplary illustration of an embodiment of a portablesystem for storing human blood, in accordance with various aspects ofthe present invention.

FIG. 2 is a schematic top view of the interior wall layer for the systemas shown in FIG. 1.

FIGS. 3A and 3B show schematic representations of the side andbottom/top walls of the system as shown in FIG. 1.

FIG. 4 is a flow chart of an embodiment of a method of storing bloodusing the system of FIG. 1, in accordance with various aspects of thepresent invention.

FIG. 5 is an exemplary graph illustrating the temperature regulatingcapability of the system of FIG. 1 using the method of FIG. 2 in a hotenvironment, in accordance with an embodiment of the present invention.

FIG. 6 is an exemplary graph illustrating the temperature regulatingcapability of the system of FIG. 1 using the method of FIG. 2 in a coldenvironment, in accordance with an embodiment of the present invention.

FIG. 6 is an illustration of the system of FIG. 1 being used in thefield in a combat situation, in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an exemplary illustration of an embodiment of a portablesystem 100 for storing materials at a given temperature range over aperiod of time, such as human blood or other temperature sensitivematerials. The embodiment of FIG. 1 shows various aspects of the presentinvention, and the system 100 generally comprises a base unit 110,having four side walls and a bottom wall. The base unit 110 alsoincludes a removable or semi-removable lid 120 for sealing the base unit110. The lid 120 may be hingedly attached to the base unit for example.The system 100 may further comprise vacuum insulation panels (ormaterial) 130 to surround and help insulate the base unit 110 and lid120, although depending on the environment in which the system 100 is tobe used, panels 130 may not be needed. The vacuum insulation panels 130have an R-value of 30 or other suitable value, and are configured suchthat a top panel 135 opens up providing access to the sealed base unit110, in accordance with an embodiment of the present invention. In anembodiment, the temperature stability of the system is significantlyenhanced by a pinwheel type attachment of the insulation panels 130 toone another at the locations of the intersection between panels 130,such as at the corners of the enclosure formed by the panels 130. Asseen in FIG. 2, the sidewalls may have insulation panels 130 with abarrier material forming the interior surfaces 132, or the barriermaterial may be provided separate from panels 130. The barrier materialforming surface 132 is configured with pinwheel type overlappingadjacent walls, such as by providing overlapping sections 134 arrangedin a pinwheel type configuration, with each successive overlappingportion 134 corresponding to the corner regions of the enclosure. Theoverlapping portions 134 provide more effective sealing of the interiorvolume of system 100, to significantly reduce any thermal losses orgains at these locations, to facilitate providing a substantiallyuniform temperature atmosphere within system 100. Pinwheel attachment oroverlapping attachment of panels 130 or of barrier material 132 at theseintersections can reduce any edge loss, to thereby maintain temperaturestability uniformly throughout the system 100.

In accordance with an embodiment of the present invention, the base unit110 and lid 120 have internal cavities containing a phase changematerial. The walls and top/bottom of the system 100 may define acontinuous cavity or discrete cavities may be provided if desired. Asshown in FIGS. 3A and 3B, examples of the walls and top/bottom of thesystem 100 have a phase change material 125 in the cavity 126. The phasechange material is preferably a gel-based material which melts andsolidifies at a certain temperature and, in doing so, is capable ofstoring or releasing energy. As a result, the phase change material canbe used to help maintain or regulate the temperature of other materials(e.g., blood). In accordance with an embodiment of the presentinvention, the phase change material is designed to change phase (i.e.,melt or solidify) at approximately 1 to 10° C., or more preferably atapproximately 4° C. As an example, a phase change such as deuteriumoxide may be used in the base unit 110 and lid 120, but other phasechange materials could be utilized which change phase at the desiredtemperatures. Using a phase change material which changes phase atapproximately 1-10 C., provides a temperature for storing bags of humanblood as an example. The base unit 110 and lid 120 constitute aremovable thermal isolation chamber (TIC). In accordance with anembodiment of the present invention, the base unit 110 can hold at least4 standard units (i.e., bags) of blood. In an embodiment, the TIC may beusable in environments in which varying pressure could be encountered,such as in military operations wherein the system 100 could be deployedin higher altitudes or underwater. In such circumstances, it may bedesirable to equalize pressure relative to the contents of the TIC. Insuch an embodiment, one or more equilibration ports 122 may be providedin the TIC, to allow equilibration with the outside atmosphere. Theport(s) 122 may be a small air port having a Tyvek (or other suitablematerial) cover there over, which will allow gaseous exchange with theoutside atmosphere, but prevent liquid exchange therethrough. Anysuitable port system to allow equilibration between the TIC and outeratmosphere is contemplated. As merely an example, an equilibration port122 may be provided in the top and bottom portions of the TIC.

The system 100 also includes a durable carrying bag 140 to hold thesealed base unit, which may be surrounded by the vacuum insulationpanels 130. The carrying bag 140 may be made of durable nylon andinclude a zipper 145 and an adjustable strap 146, in accordance with anembodiment of the present invention. Other perishable medical suppliesmay be stored in the system 100 as well, in accordance with variousembodiments of the present invention.

FIG. 4 is a flow chart of an embodiment of a method 200 of storing bloodusing the system 100 of FIG. 1, in accordance with various aspects ofthe present invention. In step 210, a thermal isolation chamber ispreconditioned at a preconditioning temperature for a predefined periodof time. The thermal isolation chamber comprises a base unit and a lidwhere the base unit has a plurality of closed walls and an open side.The closed walls of the base unit and the lid include a phase changematerial incorporated therewith which changes phase at about apredetermined storage temperature or temperature range. In step 220, atleast one bag of blood is placed into the base unit. In step 230, thelid is placed onto the open side of the base unit to seal the base unit.In step 240, the sealed base unit is surrounded with a vacuum insulationmaterial. In step 250, the sealed base unit, surrounded by theinsulation material, is placed into a carrying bag.

In accordance with an embodiment of the present invention, the base unit110 and lid 120 is preconditioned to a temperature of −20° C. for 6hours for hot weather applications or to +4° C. for 2 hours for coldweather applications, before being integrated with the vacuum insulationpanels 130 and the bag 140. As shown in FIGS. 3A and 3B, the internalcavities 127 of the base unit 110 and the lid 120 may also includethermal isolation members or fences 115, which may be provided so as tobe exposed to the phase change material within the cavities of the baseunit 110 and top 120. The members or fences 115 may be continuous layersof material, such as a thermally conductive material, which may alsohave a trigger material therewith. For example, the members 115 may be alight gauge aluminum material, which is coated with an aluminum oxide orother suitable material. The layers 115 are desirably dimensioned to belarger than the adjacent cavity and associated phase change material, soas to be exposed adjacent all of the phase change material. The phasechange material 125 is therefore filled to a point such as at 129, suchthat the members 115 are in contact with the phase change material overtheir extent. As shown in these embodiments, the members 115 in thesidewalls as shown in FIG. 3A may be flat, and disposed approximately inthe center of the cavity 127. For the bottom and top members of thesystem 100, the member 115 may have a corrugated, triangulatedconfiguration. The coating with aluminum oxide or other suitable triggermaterial used in combination with the phase change material, may then beexposed to the phase change material throughout the cavities, tofacilitate causing phase changes at a desired temperature or temperaturerange. This tends to maintain desired phase change characteristicsthroughout the side, bottom and top walls of the system 100. The thermalisolation fences thus help to dispense conductivity over the face of thewalls of the base unit 110 and lid 120, in accordance with an embodimentof the present invention. Also, a trigger agent, such as an amount ofaluminum oxide for use with a deuterium oxide phase change material, maybe used within the phase change material to stimulate the phase changematerial to change phase at the desired temperature or temperaturerange.

The system 100 is a passive system in that it does not require aninternal or external power source such as a battery, fuel cell, orgenerator. Also, the system 100 does not require any kind of activerefrigeration system once it is preconditioned.

FIG. 4 is an exemplary graph 300 illustrating the temperature regulatingcapability of the system 100 of FIG. 1 using the method 200 of FIG. 2.In this example for use in a hot environment, as the graph 300 shows, ina sustained +105° F. (+40° C.) environment, bags of human blood are heldat a constant temperature (about 4° C.) for over 60 hours and remainadequately chilled after 80 hours.

FIG. 5 is an exemplary graph 400 illustrating the temperature regulatingcapability of the system 100 of FIG. 1 using the method 200 of FIG. 2 ina cold environment. In accordance with an embodiment of the presentinvention, as the graph 400 shows, in a sustained subzero −9° F. (−23°C.) environment, bags of human blood are held at a constant temperature(about 4° C.) for over 60 hours, remaining above +1° C. after 96 hours.

In accordance with an embodiment of the present invention, the system100 carries at least 4 units (i.e., bags) of red blood cells for aperiod of at least 48 hours in an ambient temperature range of −20° C.to +40.5° C., keeping the blood contents between +1° C. and +10° C.

FIG. 6 is an illustration of the system 100 of FIG. 1 being used in thefield in a combat situation, in accordance with an embodiment of thepresent invention. In FIG. 5, an army medical person 510 isadministering a pint of blood 515 to a wounded soldier 520. The portablesystem 100 is seen sitting on the ground next to the wounded soldier520.

In accordance with an embodiment of the present invention, the physicaldimensions of the exterior of the system 100 are approximately 10″length, 9″ width, and 10″ depth. The dimensions of the interior (i.e.,the inside of the TIC base unit 110 are approximately 6″ length, 5″width, and 6″ depth. Other dimensions may be suitable for otherparticular applications and are contemplated herein.

In summary, a combat-portable, passive system safely stores blood andother perishable medical supplies over a long period of time in climatesranging from very cold temperatures to very hot temperatures. Thelayered design (i.e., TIC, vacuum insulation, bag), and the equilibriummechanism achieved by the layered design, reduce the risk of totalproduct failure.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiment disclosed, but that the invention will include allembodiments falling within the scope of the appended claims.

1. A portable system for storing human blood, said system comprising: abase unit, having a plurality of closed walls and an open side, intowhich containers of human blood are placed, and wherein said closedwalls of said base unit include a phase change material positionedtherein, the phase change material having phase change characteristicsto substantially maintain a temperature of between 2-6° C.; a lidincluding a phase change material, and wherein said lid fits onto saidopen side of said base unit to seal said base unit when storing saidcontainers of human blood; and an outer carrying bag surrounding saidbase unit and lid.
 2. The system of claim 1 wherein said base unit andsaid lid constitute a thermal isolation chamber.
 3. The system of claim1, further comprising at least one equilibrium port for equalizingpressure of the interior of the system relative to the exterioratmosphere.
 4. The system of claim 1, wherein the walls of said baseunit and said lid include cavities of said base unit and said lidinclude cavities in which said phase change material is provided.
 5. Thesystem of claim 4, further comprising a thermal isolation memberassociated with each of said cavities positioned adjacent said phasechange material therein.
 6. The system of claim 5, wherein said thermalisolation members comprise a sheet member having a trigger materialprovided therein, the trigger material facilitating control of the phasechange characteristics of said phase change material.
 7. The system ofclaim 1, further comprising a trigger material to which said phasechange material is exposed to facilitate control of the phase changecharacteristics of said phase change material.
 8. The system of claim 1,wherein the interior of the walls of said base unit are covered with aninsulating material wherein the insulating material is overlapped at theintersection of the walls.
 9. The system of claim 7, wherein theoverlapped portions are provided in a pinwheel-type configuration. 10.The system of claim 1, further comprising insulating panels surroundingthe base unit and lid.
 11. The system of claim 1, wherein thetemperature is maintained within the range of 2-6° C. for at leastforty-eight hours.
 12. The system of claim 1, further comprising atleast one cavity in which the phase change material is positioned. 13.The system of claim 12, further comprising at least one thermalisolation member within the cavity.
 14. The system of claim 13, whereinthe at least one thermal isolation member is provided with a triggermaterial thereon, which is in contact with the phase change material.15. The system of claim 13, wherein the thermal isolation member isconfigured to be flat or corrugated.
 16. A method for storing humanblood, said method comprising: preconditioning a thermal isolationchamber at a preconditioning temperature for a predefined period oftime, said thermal isolation chamber comprising a base unit and a lid,said base unit having a plurality of closed walls and an open side, andwherein said closed walls of said base unit and said lid includeinternal cavities containing a phase change material which changes phasewithin a predetermined storage temperature range; placing at least onecontainer of human blood into said base unit; placing said lid onto saidopen side of said base unit to seal said base unit; surrounding saidsealed base unit with a vacuum insulation material; and placing saidsealed base unit surrounded by said insulation material into a carryingbag.